An electrostatic chuck is used to attract and hold a processing object such as a semiconductor wafer, a glass substrate, etc., inside a plasma processing chamber in which etching, CVD (Chemical Vapor Deposition), sputtering, ion implantation, ashing, etc., are performed. The electrostatic chuck attracts and holds a substrate such as a silicon wafer, etc., using an electrostatic force by applying electrical power for the electrostatic attraction to a built-in electrode.
It is desirable to perform the temperature control of the wafer in the substrate processing apparatus including such an electrostatic chuck to increase the yield and improve the quality. Two types of performance are desirable for the temperature control of the wafer. One type of performance is the temperature uniformity in which the temperature distribution in the plane of the wafer is caused to be uniform. The other type of performance is temperature controllability in which a difference is deliberately provided to the temperature in the plane of the wafer. The performance of the heater built into the electrostatic chuck is one important component of the temperature control of the wafer. Generally, the temperature uniformity has a trade-off relationship with the temperature controllability.
Higher throughput of the substrate processing apparatus also is desirable. To realize higher throughput of the substrate processing apparatus, it is favorable for the thermal capacity of the heater built into the electrostatic chuck to be relatively small.
An RF (Radio Frequency) voltage (high frequency voltage) is applied in the processes of wafer patterning. When the RF voltage is applied, a general heater is affected by the high frequency waves and generates heat. The temperature controllability degrades thereby. Also, when the RF voltage is applied, a leakage current flows in the equipment side. Therefore, a mechanism such as a filter or the like is necessary on the equipment side.
In the case where the heater is built into the electrostatic chuck, the reliability of the method (e.g., the coupling method) used to build the heater into the electrostatic chuck is one important component.
In the processes of the plasma etching apparatus, etc., plasma of various intensities and various distributions is irradiated on the wafer. When the plasma is irradiated on the wafer, it is desirable to control the temperature of the wafer to be a temperature suited to the process. Also, when the plasma is irradiated on the wafer, temperature uniformity and temperature controllability are desirable. To increase the productivity, it is desirable to cause the temperature of the wafer to reach the prescribed temperature in a relatively short period of time. High reliability is desirable for the electrostatic chuck and the wafer even for abrupt temperature changes, when heat is supplied, and when a high frequency voltage is applied. It is difficult to satisfy such needs simultaneously.